The conventional fan, shown in FIGS. 1, 2 and 3, comprises a frame 11 and a fan 12. The frame 11 has a circular wall, a hub 111 connected to the fan and a plurality of ribs 112 extending outwards from the hub 111 with the hub 111 positioned at the central region of the frame 11. The fan 12 is axially positioned on the hub 111.
An outlet 113 is formed between two adjacent ribs 112 of the frame 11 for guiding the air flow. An outlet 114 is formed at a side opposite to the outlet 113 to lead the air into the frame 11.
To assemble the fan 12 to the heating element 13, for instance, the heat dissipater, a side of the hub 111 of the frame 11 is faced to the heating element 13, and a plurality of securing elements 14 is penetrated through the frame 11 to secure to heating element 13. Thus, the outlet 113 faces the heating element 13.
However, the conventional design has defects, for example, because the outlet 113 facing the heating element 13 has the multiple ribs 112, when the fan 12 is operated, air flows passes through the outlet 113, the ribs 112 block some of the air from flowing out from the outlet 113. Thus, the heat dissipation effect is adversely affected, and also the noise is increased.
Furthermore, the hub 111 and the ribs 112 are positioned between the fan 12 and the heating element 13 with a distance between the fan 12 and the heating element 13. When the air flows due to the operation of the fan 12, the air pressure decreases due to the distance between the fan 12 and the heating element 13, and the air pressure reaching the heating element 13 is correspondingly decreased to adversely affect the heat dissipation efficiency.